The invention relates to a process for manufacturing bimetallic coins and medals.
Bimetallic coins or medals comprising a peripheral ring and an inner insert have already been described.
When it is desired to prepare such coins from two distinct metallic elements of which one is in the form of a ring and the other in the form of an insert, features must, of course, be used to connect these two elements. This connection must be such that, after assembly, the two elements form a single coin comprising on each of its faces the desired design or lettering, avoiding the insert pivoting about its axis inside the ring. The problem of connection of two elements of this type has been the subject of research in very different fields and various solutions have been recommended. In the more specific field of coins, a solution has been recommended in EP-A-0 080 437 for the preparation of bimetallic flans intended for mintage; the connection features described in this document are constituted by a certain number of teeth on an inner face of the ring. An inner insert is positioned so that its periphery is tangential to upper faces of the teeth and creeping or flowing of the metal of the insert is caused by pressure so that the teeth are shut up by this metal. This technique presents a certain number of drawbacks, particularly due to the necessity of having to manufacture a ring comprising the teeth and of having to effect a creeping or flowing of the metal on the surface of the coins, which may often lead to visible irregularities on the final coins obtained.
The present invention relates to a process for manufacturing bimetallic coins or medals, by connection of a ring with an insert, which overcomes the difficulties encountered when carrying out the process described in EP-A-0 080 437.
The process of EP-A-0 080 437 also conforms to the process described in JP-A-58 003 743.
The purpose of the process in accordance with this invention is to overcome the drawbacks of the known processes, and particularly to avoid the necessity of having to use two successive strikings in order to make each coin or each medal.
Another main purpose of the present invention is to solve the technical problem of finding a solution rendering the operation of assembling the two elements easier and also preferably of facilitating the minting.